Browning .30 cal
In 1919, John Browning set to creating a lighter version of the ubiquitious M1917, that had seen such success in the last days of the first world war, and would see that success continue in the US until the introduction of the M-60. Originally chambered for the M1906(.30-06) ball cartridge, production later switched to chambering for the .30 cal M2 ball cartridge. Utilizing a closed bolt feed system, the machine gun was fed initially from a woven cloth belt, and later from a disintegrating metal belt. Upon the design deciscion to lighten the weapon by making it air cooled, this closed bolt system created a dangerous problem. If the machine gun had been fired for a prolonged duration, it could cause the next round to cycle into a red hot chamber, resulting in a cook off. While not a problem if firing until a belt is depleted, when loading a new belt, this could cause the bolt and extraction system to recoil back while charging, and dislocate the users thumb. With help from the design and production firm Fabrique Nationale de Herstal, the M1919 was developed into the M2 AN(Army-Navy) for aerial use. With thinner, lighter components, and more effective air cooling, this new variant of the 1919 weighed 2/3 of the original design, with an improved fire rate of 1900 rpm, though the excessive barrel wear kept the rate of fire down to 1350 rpm. Used in both fixed and flexible mounts, the M2 AN saw use throughout the world, until the .50 cal M2 made its debut in 1943. Variants and Derivatives .303 Manufactured by the British in order to utilize the standard .303 round, for use on fighter aircraft until the advent of the Hispano-Suiza HS.404, and on bombers throughout the war. Here the "cook off" problem truely became catastrophic. The more sensitive british cordite was far more prone to cook off, and as such, the british had to convert to a more expensive and complex open bolt system, thereby eliminating the problem M1919 The base line production model. The A1 had a shorter, lighter barrel, in attempt to create a moremanueverable weapon for mobile infantry use, though its still relatively heavy weight lead to it being rarely used in such a manner. The A2 was another lightweight developement, designed for calvary units. By WWII, this version had been replaced by the improved A3. Easily the most widely produced model, was the A4. After resignation to the fact that the 1919 was more likely to be used in fixed emplacements than on the move, the A4 was fitted with a longer, heavier barrel. This version was used on fixed and flexible mounts by infantry and vehicles. Widely exported after WWII, the A4 continues to be used on small vehicles around the world. Two variants existed for vehicle use. The A5, with an extended charging handle, and the A4E1, which was an A4 refitted with an extended charging handle. AN/M2 Developed as an aerial use variant, the AN/M2 sported a thinner barrel and thinner reciever walls. A derivative was built by colt as the MG40. Browning .303 MKII Adopted by the RAF and manufactured by Vickers Armstrong and BSA to fire the .303 British round, this variant had a few modifications for use in aerial applications. Ckm wz.32 Polish variant chambered in 7.92mm T33 A infantry variant produced from field modifications of the AN/M2, it was traditionally fitted with an A6 butt stock, and a 1918 BAR bi-pod and rear sights. A personalised version, used by post-humous winner of the Medal of Honor, Corporal Tony Stein, was fitted with the buttstock from an M1. M37 A coaxial variant, this version could be belt fed from the left or right side, and featured an extended charging handle. Several, designated M37E1, were chambered for 7.62 x 51mm until the M73 could be fielded. MK21 Mod0 Navy variant chambered for 7.62 mm NATO